1. Field of the Invention
The present invention relates to a switching power supply provided with a switching circuit and a rectifying/smoothing circuit.
2. Description of the Related Art
For use as a switching power supply, various types of DC (Direct Current)-DC converters have been proposed and actually used. Such DC-DC converters are often of a type in which the switching operation of a switching circuit (inverter circuit) causes a switching of a DC input voltage. The switching circuit is the one connected to the primary winding of a power conversion transformer (transformer element). The resulting switching output (inverter output) is then led to the secondary winding of the power conversion transformer (transformer). The voltage appeared in the secondary winding as such as a result of the switching operation of the switching circuit is rectified by a rectifying circuit, and then is converted into DC by a smoothing circuit before output.
Such a DC-DC converter is not the only example for use as a switching power supply, and various types of AC (Alternating Current)-DC converters have been also proposed in which an AC input voltage is converted into a DC output voltage. An example includes Japanese Patent No. 3486603.